Polish J. of Environ. Stud. Vol. 20, No. 3 (2011), 565-569

Original Research Diversity of Three Species of the (, ) Parasitizing in Poland

Joanna N. Izdebska*, Sławomira Fryderyk

Laboratory of Parasitology and General Zoology, Department of Invertebrate Zoology, University of Gdańsk, Piłsudskiego 46, 81-378 Gdynia, Poland

Received: 19 July 2010 Accepted: 4 January 2011

Abstract

The occurrence of hair follicle (Acari, Demodecidae) was investigated in dogs from Gdańsk Pomerania, Poland. The three species of demodectic mites (Demodex canis, D. cornei, and D. injai) specific to dogs not only differ morphologically, but are also found on different areas of the hosts’ . Parasitic adap- tations involve size and shape of the body, which is elongated and worm-like, providing a specific adaptation to life in hair follicles, in various glands and their ducts or epidermis. The differentiation in structure, biology, and microhabitats of these mites may be associated with the occurrence in dogs of forms of demodecosis with different symptoms and courses.

Keywords: Demodex, , demodecosis, parasites, infestation

Introduction described later in studies that applied scanning microscopes [8-10]. However, the descriptions of these species remain The Demodex parasites were the first of the insufficient – D. injai has been described based on homoge- Demodecidae family (Acari, ) discovered nous material from the U.S., while D. cornei descriptions by scientists and to date have been thoroughly researched. contain incomplete measurements and are based on a small The canine demodecosis they cause is the most frequently sample of specimens to boot. No description of the juvenile occurring skin diseases in veterinary medicine. Even with stage has been provided for this species. numerous communications and studies on canine demodi- The basic diagnostic methods used in detecting mites cosis, its symptoms, and methods of treatments, knowledge when is suspected are based on microscopic of etiological factors of this type of parasitosis remains analysis of skin scrapings. The disease is confirmed based incomplete. For over a hundred years, any reported case has on detection and identification of Demodex spp. It seems been tied to one species only: viz. Demodex canis [1]. relevant, then, to find marker features in terms of morpho- Miscellaneous symptoms, the course of the disease, and logical details or body proportions that would facilitate dis- problems with treatment have suggested the existence of a tinguishing species. more complex etiology. Even though D. canis has been described in detail by many authors [1-5], only recently has a second species of Demodex mites been identified: Experimental Procedures [6]. A number of communications on infes- tations caused by the so-called short-bodied form, regarded The material comprised skin segments collected from by some authors as a separate species, Demodex cornei [7], 25 dogs, of which 20 had no symptoms of demodicosis and 5 had localized symptoms. The skin samples were taken *e-mail: [email protected] from dead dogs in Gdańsk Pomerania between 2003 and 566 Izdebska J. N., Fryderyk S.

2009. The skin samples were taken from the head (, Demodex species, less frequently as a result of synhospital cheek, nose, ear, upper lip), fore and hind groins, limbs (the infestation [12-14]. The disease usually entails a decrease in knee region), belly, and genital-anal regions. They were the host’s immunity [17, 18]. The symptoms of demodico- preserved in 70% ethanol solution, then analyzed using the sis have been dealt with extensively in the literature, and standard method of skin digestion [11]. The digested sam- many studies describe the development and course of the ples were examined under a phase-contrast microscope. All disease, various symptoms and variants, histopathological the mites found were mounted in Faure’s medium. changes, diagnostic methods, and treatment, but lesions Additionally, a retrospective study was carried out on linked to canine demodicosis were always attributed to D. mass microscopic sections made of skin scrapings from 100 canis [3, 19-25]. However, today we know that in many dogs with symptoms of demodicosis dating back to the cases the etiological factors might not have been correctly 1970s. 300 microscope slides of hair follicle mites present established and the cause of the infestation in question asymptomatically in 90 dogs were analyzed retrospective- might, in fact, lie in one of the three species of the genus ly. The slides were from our laboratory’s collection and had Demodex or synhospital infestation. Descriptions of infes- been preserved in Canada balsam or polyvinyl lactophenol tation brought about by other species have only recently in 1973-77. been reported, so data on infestation with D. cornei comes from China, Japan, Greece, and Poland, and with D. injai from the U.S., Spain, and Poland [6, 8, 10, 15, 26, 27]. Results and Discussion Taxonomical Characteristics of Demodex spp. Occurrence and Infestations of Particular in Dog Demodex Mites Demodecid mites are small, tiny, usually with elongate In the current study, Demodex canis has been found on bodies with four pairs of short, stump-like, forward-point- 46% of the dogs. In the study by Stankiewicz et al. [12], ing legs displaced toward the front; stiletto-like chelicerae; based on a large sample (approximately 39,000 dogs in the three-segmented palpi; a massive hip element; and 4-5 rod- Warszawa region), D. canis was found on 85% of hosts, but shaped bristles on the distal segment. The body is separat- demodicosis was diagnosed only in 0.75% of dogs. The ed into three distinct tagmas. The small gnathosoma has a first observation conducted in the Pomerania region con- trapezoidal or rectangular shape; the podosoma supports firmed asymptomatic existence of this parasite on 38% of the much-reduced legs with a pair of forked claws, which the 100 dogs examined at that time [13]. Subsequent stud- usually protrude only slightly beyond the line of the ies describing infestation with D. canis in dogs from podosoma; on the ventral side of most adult mites the Gdańsk Pomerania also show a high level of extensiveness epimeral plates are readily discernible. The opisthosoma is as well as the usually asymptomatic nature of the transmis- usually elongated with cuticular striations [3, 5, 28, 29] sion [14, 15]. Thus, it is not surprising that in the current (Fig. 1). study the typical symptoms of canine demodicosis were found in only a few dogs as localized symptoms. Demodex injai was found in three dogs. Skin lesions were visible on the whole body, on the head and limbs in particular. However, the frequency of occurrence of this GNATHOSOMA epimeral plate parasite remains unknown, as it was found neither in the course of retrospective studies nor in earlier studies on dogs from the Pomerania region [14]. The first report of D. injai legs occurrence has been received only very recently [15]. Most PODOSOMA likely this species displays low extensiveness of infestation. Demodex cornei was found on 8% of dogs currently under study, but no symptoms of demodicosis were deter- mined. In the retrospective analysis this species was found vulva in 6% of the dog sample with demodicosis symptoms. It is difficult to establish which symptoms should be tied to its presence in the context of synhospital infestation with D. canis, which was a dominant species in this case. No data OPISTHOSOMA is available about its occurrence in other parts of Poland – it was first reported in Gdańsk [15]. Canine demodicosis is indeed the most frequently diag- nosed skin disease in veterinary medicine and Demodex spp., responsible for its symptoms, constitutes a typical canine parasite fauna [15, 16]. However, infestation is usu- ally asymptomatic. Skin symptoms on the host usually appear due to excessive multiplication of one of the Fig. 1. Morphology of Demodex canis (female, ventral view). Diversity of Three Species of the Genus... 567

Table 1. Comparison of characteristic of Demodex spp. living on a domestic dog. D. canis D. cornei D. injai male female male female male female 26.9 25.2 19.9 19.1 22.3 23.1 Length of gnathosoma [21-31] [18-30] [15-26] [15-28] [21-25] [21-26] SD 2.5 SD 3.1 SD 2.6 SD 3.9 SD 1.2 SD 1.7 23.7 21.9 21.4 20.9 28.8 28.6 Width of gnathosoma [19-30] [16-29] [18-26] [16-28] [25-32] [25-32] SD 3.7 SD 3.4 SD 2.4 SD 4.5 SD 2.3 SD 2.2 63.8 63.4 52.1 53.9 87.3 82.3 Length of podosoma [50-81] [58-75] [39-65] [40-66] [82-94] [66-88] SD 9.2 SD 3.4 SD 9.2 SD 7.6 SD 4.0 SD 5.4 38.8 37.2 35.9 37.6 43.5 44.4 Width of podosoma [33-46] [28-41] [29-40] [28-39] [35-47] [40-49] SD 3.7 SD 2.5 SD 3.2 SD 4.6 SD 3.5 SD 3.9 116.5 133.1 46.2 65.4 264.7 224.3 Length of opisthosoma [74-166] [100-167] [36-54] [47-99] [203-340] [161-281] SD 24.3 SD 17.6 SD 4.2 SD 12.6 SD 57.0 SD 49.1 33.3 34.6 35.3 33.2 35.6 36.7 Width of opisthosoma [28-40] [25-42] [23-40] [27-40] [31-40] [33-41] SD 3.9 SD 3.6 SD 4.5 SD 4.2 SD 3.7 SD 3.2 195.2 226.0 120.8 139.4 371.8 330.9 Total length of body [146-251] [177-265] [93-136] [120-165] [309-455] [245-396] SD 33.2 SD 20.1 SD 13.2 SD 17.9 SD 58.4 SD 45.5 Ratio of length to width 4.5-5.5 5.9-6.4 3.2-3.5 3.6 -4.2 8.5-9.5 6.5 : 7.6

Ratio of length opisthosoma 51 59 39 43 71 68 to body length [%] [50-59] [56-63] [38-40] [39-50] [66-74] [66-70] Microhabitat hair follicles epidermis sebaceous glands

Adaptations for parasitism are in this case applicable to Demodex canis is an elongated species, the opisthoso- both the size and the shape of the body. Due to the adapta- ma becoming slender and sharp toward the terminal end. tion for living in the host’s tissue, the Demodecidae suf- Opisthosoma long and slender, gradually tapering to the fered an extreme reduction in number of morphological ele- posterior end. Capitulum (gnathosoma) of moderate width, ments [30], e.g. they have only a few, strongly reduced bris- being widest at the base, where it is slightly wider than tles, which makes species identification difficult. In view of long; the two spines on its dorsal surface (supracoxal setae) the reduction of a number of morphological features, there are very short and pointed. Epimeral plates are trapezoidal are not many characteristics that can be used for diagnostic in shape. Male – size very variable, specimens of this sex purposes in demodecid . The following are usual- being sometimes much shorter than females (Figs. 1, 2, ly taken into account: the shape of the setae (supracoxal Table 1). spines and subgnathosomal setae); the number, position and Demodex cornei have a short, wide body; compared shape of the pedipalp claws/setae; the position and length of with D. canis and D. injai, it has a stumpy body shape. The the aedeagus (male) and genital opening in the female; the dorsal surface of the podosoma is flat, while shallow trans- presence of the opisthosomal organ; and the presence of verse grooves are observed over the entire opisthosoma. The epimeral plates and their shape or the shape of the posteri- supracoxal spines of the dorsal gnathosoma have centrally or section of the opisthosoma [28, 29, 31, 32]. orientated spines. The epimeral plates are almost rectangular. 568 Izdebska J. N., Fryderyk S.

There is a band-like plate dividing the lower edge of the fourth coxisternal plate and the opisthosoma (Fig. 3, Table 1). Demodex injai is a long-bodied species more than twice the length D. canis. Each supracoxal spine is a conical peg somewhat recessed into the gnathosomal cuticle. An opishosomal organ (proctodeum) is currently known as a narrow tube (Fig. 4, Table 1). Additionally, the three Demodex species show not only morphological differences but they also settle in different habitats on the canine skin. D. canis lives in the hair folli- cles, while D. cornei is always found in the corneal layer of the epidermis and D. injai is linked to glands and their out- going ducts [6, 9, 15]. In Demodecidae, the shape, dimen- sions and proportions of the body constitute a specific adap- tation to the occupied microhabitat, which was confirmed here – D. canis resembles other species linked to hair folli- cles, e.g. in . The long-bodied D. injai, on the other hand, is linked to species with similar locations in ungulates or bats. The small size and propor- Fig. 2. Demodex canis – male and female. tions of D. cornei resemble analogical species in the feline epidermis or the golden hamster [29, 32-35]. Topical and host specificity is most likely a typical feature of the evolu- tionary development of Demodecidae which, within partic- ular host species, adapted to various types of dermal micro- habitats, thus creating specific adaptation to life, nutrition, location, and transmission. This led to the emergence, with- in particular host taxons, of synhospital demodectic species of different topography and specificity toward dermal tis- sues/elements. Analogical sets/groups of synhospital species were described on rats (four species), cattle (three species), horse, sheep, and cats (two species in each) [28, 32]. Undoubtedly, species with different localtion and, con- sequently, with different adaptive strategies can cause infes- tation of different courses and varied symptoms. This is Fig. 3. Demodex cornei – male (ventral and lateral view) and why, when diagnosing canine demodicosis, the correct female. identification of the demodectic species, which is the etio- logical factor, is of utmost importance. However, features used in the taxonomy of Demodecidae are not very helpful in veterinary diagnostics. The taxonomy of these miniature mites is based on the analysis of bristles that are a few micrometers long or other elements hard to discern and identify. The current morphometric analysis of Demodex spp. infesting dogs is based on a study of a representative sample of specimens (at least 100 specimens of a given sex for each species) and reveals significant diversity in terms of size and body proportions (Table 1). It seems that these features might prove useful in veterinary diagnostics.

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